The present invention concerns an end piece for a tube mantle which is separately manufactured.
Packaging tubes are made mainly by two different methods: by extruding from one single piece of material, or by combining a tube that has been rolled of thin sheet, for instance of foil, and thereafter seamed, to an end piece. Joining of the mantle made of foil to said end piece is accomplished by the aid of a cuff or equivalent clamping member which is pressed upon the end piece to impact the margin of the mantle therebetween, whereby a tight and leak-free joint is obtained. The assembly comprises many work steps compared e.g. with the manufacturing of a deep-drawn tube, owing to the number of components. A manufacturing procedure of this type has for instance been disclosed in the Finnish patent application No. 814142.
In the U.S. Pat. No. 3,817,427 is encountered a tube end piece where at the juncture of a conical part and a cylindrical part has been shaped a projection which is supposed to be conducive to faster assembly similarly as the invention now to be presented. The bending downward of this projection to the purpose of affixing the mantle is based on plastic deformation of the material. In the case of metals, a deformation of this magnitude is doubtful, particularly in view of achieving tight sealing; in the case of plastic materials, again, softening of extensive areas by heating is required for this operation to be successful--as is indeed mentioned in the reference. The heating of plastics is slow and energy-consuming, and in the final product a nodule is formed at the seam; this nodule impedes the rolling of the tubes along a straight line e.g. on automatic tracks.